Doublescan; Diagnostics Function: Dirt And Error Signal Output; Test Input - Siemens SIMATIC FS400 Anleitung

4.2.5 DoubleScan

The receiver provides an option for increasing the availability with difficult
environmental conditions. It doesn't switch off immediately after a beam interruption,
but rather waits to see if the interruption is still present in the next scan, before the
receiver switches the OSSDs off. If DoubleScan is active, the receiver switches to the
OFF state as soon as the same beam is interrupted in two consecutive scans.
Fig. 4.2-4: Example: DoubleScan, scan factor H = 2
WARNING
The change to DoubleScan mode is described in Chapter 8. It results in an extension
of the response time. The values are shown in the tables in Chapter 12. The safety
distance to the danger point must be recalculated in accordance with Chapter 6.1!
4.3

Diagnostics function: Dirt and error signal output

For diagnostic purposes SIMATIC FS400 3RG7845 has a short circuit-proof "Weak
Beam/Error Indication" signal output for forwarding to the machine control unit.
Information on connection of the signal output and connection examples can be found
in Chapter 7.2.2, Chapter 7.3.2 and Chapter 7.5.2.
4.4

Test input

As a type 4 AOPD, SIMATIC FS400 3RG7845 has a constant self-monitoring function
that independently detects errors in the system as well as cross and short circuits on
the output cables of the machine interface. An external test signal is not required for
this. To test the downstream contactors, an external control (e.g. protective
combination) via activation of the test signal on the transmitter can switch off the OSSD
outputs of the receiver and test the drop-out of the switching elements. The test signal
time is a maximum 3 seconds. If this test function is not required, the transmitter's
connecting terminals (terminal 3 and 4) are connected with a jumper. For this, see also
Chapter 7.2, Chapter 7.3 and Chapter 7.5
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